arch/x86/events/probe.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/export.h>
   3 #include <linux/types.h>
   4 #include <linux/bits.h>
   5 #include "probe.h"
   6
   7 static umode_t
   8 not_visible(struct kobject *kobj, struct attribute *attr, int i)
   9 {
  10         return 0;
  11 }
  12
  13 /*
  14  * Accepts msr[] array with non populated entries as long as either
  15  * msr[i].msr is 0 or msr[i].grp is NULL. Note that the default sysfs
  16  * visibility is visible when group->is_visible callback is set.
  17  */
  18 unsigned long
  19 perf_msr_probe(struct perf_msr *msr, int cnt, bool zero, void *data)
  20 {
  21         unsigned long avail = 0;
  22         unsigned int bit;
  23         u64 val;
  24
  25         if (cnt >= BITS_PER_LONG)
  26                 return 0;
  27
  28         for (bit = 0; bit < cnt; bit++) {
  29                 if (!msr[bit].no_check) {
  30                         struct attribute_group *grp = msr[bit].grp;
  31
  32                         /* skip entry with no group */
  33                         if (!grp)
  34                                 continue;
  35
  36                         grp->is_visible = not_visible;
  37
  38                         /* skip unpopulated entry */
  39                         if (!msr[bit].msr)
  40                                 continue;
  41
  42                         if (msr[bit].test && !msr[bit].test(bit, data))
  43                                 continue;
  44                         /* Virt sucks; you cannot tell if a R/O MSR is present :/ */
  45                         if (rdmsrl_safe(msr[bit].msr, &val))
  46                                 continue;
  47                         /* Disable zero counters if requested. */
  48                         if (!zero && !val)
  49                                 continue;
  50
  51                         grp->is_visible = NULL;
  52                 }
  53                 avail |= BIT(bit);
  54         }
  55
  56         return avail;
  57 }
  58 EXPORT_SYMBOL_GPL(perf_msr_probe);